Two Ropes, Forty-Five Minutes

The problem
each rope burns in 60 min · unevenlyrope Arope Bmeasure exactly 45 minutes

You have two ropes and a lighter. Each rope, lit at one end, takes exactly 60 minutes to burn through — but they burn unevenly: the first half of a rope might take 58 minutes while the second half takes 2.

Measure exactly 45 minutes. No clock allowed.